If a language preference is not specified by the UserLocale property of IUpdateSession2, or if the IUpdateSearcher interface is not created by using IUpdateSession::CreateUpdateSearcher, the information that is returned by this property is for the default user interface (UI) language of the user. If the default UI language of the user is unavailable, Windows Update Agent (WUA) uses the default UI language of the computer. If the default language of the computer is unavailable, WUA uses the language that the provider of the update recommends.